Portable base station network for local differential GNSS corrections

Abstract

A DGNSS-based guidance system, wherein a rover receiver first utilizes data from a master base station transceiver, a DGNSS reference network, or some other differential source to compute a differentially corrected location to establish a reference DGNSS relationship. Using this location and data observed only at the rover, the rover computes an internal set of differential corrections, which set is stored in computer memory, updated as necessary, and applied in future times to correct observations taken by the rover. As the rover enters into areas of other base station receiver reference networks, the rover transceiver will send positional information it receives from the master base station to the new, secondary base station. The secondary base station then calibrates its own reference information using information sent from the original master base station.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is: 
     
       1. A positioning system for differentially computing a location of a rover unit with a differential Global Navigation Satellite System (GNSS) including a master base station with a master base GNSS antenna, a master base GNSS receiver coupled to the base GNSS antenna and a master base communication system including a master base transmitter; and a secondary base station with a secondary base GNSS antenna, a secondary base GNSS receiver coupled to the secondary base GNSS antenna and a secondary base communication system including a secondary base transmitter;
 the positioning system including a computer system configured to: 
 calculate a position offset corresponding to an offset between differential corrections created by the master base station and the secondary base station; 
 transmit the position offset to the rover unit as the rover unit transitions from a coverage area for one of the master and secondary base station to a coverage area for the other one of the master and secondary base station; and 
 cause the rover unit to correct a rover GNSS-defined position with the position offset. 
 
     
     
       2. The positioning system of  claim 1 , wherein the computer system is further configured to:
 calculate different position offsets for different locations of the secondary base station; 
 save the different position offsets for the different locations of the secondary base station; 
 determine a current GNSS location for the secondary base station; 
 identify one of the different locations closest to the current GNSS location as a closest GNSS location; and 
 use one of the saved position offsets for the closest GNSS location for the secondary base station when a distance between the current GNSS location and the closest GNSS location is less than a threshold distance. 
 
     
     
       3. The positioning system of  claim 1 , wherein the computer system is further configured to transmit the position offset to the master base station and the secondary base station. 
     
     
       4. The positioning system of  claim 1 , wherein the computer system is further configured to:
 generate an average for position offsets between the master base station and different secondary base stations; and 
 apply the average to the rover GNSS-defined position. 
 
     
     
       5. The positioning system of  claim 1 , wherein the computer system is further configured to:
 receive differential corrections from the master base station and the secondary base station when the rover unit is located in an overlapping coverage area of the master base station and the secondary base station; and 
 use the differential corrections from the master base station to correct the rover GNSS-defined position in the overlapping coverage area. 
 
     
     
       6. The positioning system of  claim 5 , wherein the computer system is further configured to:
 detect a blocked-signal area within the overlapping coverage area where signals from the master base station are blocked; and 
 use the differential corrections from the secondary base station to correct the rover GNSS-defined position in the blocked-signal area. 
 
     
     
       7. The positioning system of  claim 1 , wherein the computer system is further configured to:
 identify a master set of location coordinates for the master base station; 
 identify a position offset of the secondary base station from the master set of location coordinates; and 
 transmit the position offset to the secondary base station to align the differential corrections for the secondary base station with the differential corrections for the master base station. 
 
     
     
       8. A method for using a computing device to compute a location of a vehicle, comprising:
 receiving first differential correction data for a master base station; 
 receiving second differential correction data for a secondary base station; 
 identifying a position shift between the first differential correction data and the second differential correction data; 
 sending the position shift to the secondary base station to adjust the second differential correction data; 
 using the position shift to correct a vehicle GNSS-defined position. 
 
     
     
       9. The method of  claim 8 , further comprising:
 using the first differential correction data to correct the vehicle GNSS-defined position while the vehicle is in a first coverage area of the master base station; and 
 using the second differential correction data to correct the vehicle GNSS-defined position while the vehicle is in a second coverage area of the secondary base station. 
 
     
     
       10. The method of  claim 8 , further comprising sending the position shift to the secondary base station when the vehicle moves into an overlapping region of the first coverage area and the second coverage area. 
     
     
       11. The method of  claim 10 , further comprising:
 detecting a blocked-signal area within the overlapping region where signals from the master base station are blocked; and 
 using the adjusted second differential correction data from the secondary base station to correct the vehicle GNSS-defined position when the vehicle is in the blocked-signal area. 
 
     
     
       12. The method of  claim 8 , further comprising deriving the position shift between the first differential correction data and the second differential correction data relative to the master base station. 
     
     
       13. The method of  claim 8 , further comprising:
 saving different GNSS base locations and associated differential correction data for the secondary base station; 
 determining a current GNSS location of the secondary base station; 
 identifying one of the different GNSS base locations closest to the current GNSS location; and 
 use the saved differential correction data for the identified one of the different GNSS base locations for the secondary base station. 
 
     
     
       14. The method of  claim 8 , further comprising:
 saving GNSS locations for the secondary base station; 
 determining a current GNSS location of the secondary base station; and 
 generating differential correction data for the current GNSS location by averaging the differential correction data for some of the saved GNSS locations closest to the current GNSS location. 
 
     
     
       15. The method of  claim 8 , further comprising reusing the position shift for new locations of the secondary base station. 
     
     
       16. A positioning system for computing a location of a rover unit, comprising:
 a computer system configured to: 
 receive first differential corrections from a first base station; 
 receive second differential corrections from a second base station; 
 calculate a position offset between the first differential corrections from the first base station and the second differential corrections from the second base station; 
 send the position offset to the second base station to calibrate the second differential corrections; and 
 use the position offset to correct a vehicle GNSS-defined position. 
 
     
     
       17. The positioning system of  claim 16 , wherein the computer system is further configured to send the position offset to the second base station when the vehicle moves into an overlapping coverage area of the first and second base stations. 
     
     
       18. The positioning system of  claim 17 , wherein the computer system is further configured to:
 detect a blocked-signal area within the overlapping coverage area where signals from the first base station are blocked; and 
 use the calibrated second differential corrections from the second base station to correct the vehicle GNSS-defined position when the vehicle is in the blocked-signal area. 
 
     
     
       19. The positioning system of  claim 16 , wherein the computer system is further configured to calculate the position offset between the first differential corrections and the second differential corrections relative to a known location of the first base station. 
     
     
       20. The positioning system of  claim 16 , wherein the computer system is further configured to:
 save different GNSS base locations and associated differential corrections for the second base station; 
 determine a current GNSS location of the second base station; 
 identify one of the saved GNSS base locations closest to the current GNSS location; and 
 generate the differential corrections for the current GNSS location based on the differential corrections for the closest one of the saved GNSS base locations. 
 
     
     
       21. The positioning system of  claim 20 , wherein the computer system is further configured to generate the differential corrections for the current GNSS location by averaging the differential corrections for multiple saved GNSS locations closest to the current GNSS location.